Temperature-actuated mechanism



-Feb. 13, 1940. D. R. LAMBERT TEMPERATURE-ACTUATED MECHANISM FiledDec.16, 1937 Patented Feb. 13, 1940,

PATENT Omar" TE PERATUR CTUATED MECHANISM} Donald Rudolf Lambert,barshalton, England Application December 16, 1937, Serial No. 186,230'In Great-ZBritain January 11, 1937 p The present invention relates totemperature I j actuated mechanisms wherein theactuating element isconstituted by a bi-metallic' member which, owing to itsinherentconstruction, is de- .-formed on alteration of temperature.

known to use such a device directly to operate I a make-and-breakcontact or for other purposes wherein a small mechanical movemen'tonlyis required, i

It is onerof the vention to produce atemperature-actuated mechanism,operation of which resultsvin a movement considerably greater in forceand degree than rnetallic strip. j A further object-of 'duction oftemperature-actuated mechanism .of

simplified construction and oflmor e certain acanalogous device P tionas comparedwith any hitherto proposed.

Another object of the invention is to produce mechanism wherein abhmetallic member is employed, on being subjected: to temperaturevariation,to bring a toggle or knucklejoint into such spring, may becomeeilective in generating an ultimate movement very much greateriniextent"and force thanis feasible by thedirect' application ofthe deformation ofa bi-metallic strip.

utilize the ultimate movement of mechanism controlled. by temperaturevariation for the actua-. H tion of a knife switch, for operating somemee. chanical device such, for example, as a belt-Shiite. ing mechanismor for any other purposewherein an action comparable in; extentand forceis re quired.

With the aboveand other objects in View, the invention comprises 1 atemperature-actuated toggle or knuckle joint mechanism wherein either,

or both of themelnbers. constituting the joint is or are of bi-metallicconstruction, the nature and dispositionof the dissimilarmetals,,and,,the

arrangement of the members being such ;that,[ .on a given alterationoi-temperature, movement, of themembers occurs fromthe set or stableposition to an unstable position wherein, by the ap:; piication of anexternal force, such'as aispring, 1

llapse of thetoggle or knuckle mechanism ensu The temperature of thebi-metallic strip strips maybe governed by that ofsurrounding 131 othersuitable manner.

ii Claims.

main objects of the present in the invention is the' proconditionthatsome external force,.such as a Still another object of. theinvention 1 is ..to-

aS'Ol liquid or of a solid body, bythe passage gh the strip or'strips ofan electric current invention will be I better from the followingdescription read in connection with the accompanying drawing, wherein;

Figure l is aside view of the simplest form of mechanism, 1, p Q

Figures 2 and Kare-respectively side view and plan of a modificationwherein the two members posite end of which is attached by a pin 5 to alever 6, hinged on a fixed pivot i, and constituting means whereby themovement desired'on collapse of the toggle or knuckle joint may betransmitted to the deviceto be operated. It will be observed that thepivot 3 lies slightly to one side oi a straight line joining the pivots2 and 5, the arrangement being such that, on change of temperaturein apredetermined direction according to the construction of the bi-metallicmemfber i, that member is deformed so thatthe pivot 3 is moved onto andeventually across the line joining the pivots '2 and 5; Under theseconditions a force such as that of a spring or weightcollapses to theposition shown in chain-dotted lines, thusallowingthe movementofthelever ti about its pivot 1 indicated. Re-setting of the mechanismisefl'ected by hand or equivalent external agency. n

A feature which distinguishes the use of a1 bi-metallic member inaccordance with the presfact that, as it constitutes one of the membersof a, toggle .or knuckle joint, it is pivoted at both ends rather thanhaving one of its endsjfixed as has commonly been the case heretofore,Accordingly, means must be taken to constrain the movement of thebi-metallic member l relatively to the other members of the mechanism inorder to ensure that, on deformation resulting from change oftemperature movement of the pin 3 shall occurrather than merely adisplacement of the central portion of the bi-metallicmem ber. In the,present example the necessary jre-. straint iseffected by the provisionof a'stop 8 which, when the mechanism is in'its settor stable positionasshown, abuts against an intermediate, point oftheQbi-metallic member]1.; ,I f the mechanism be: designed to function on increase oftemperature,-the bi-metallic member must be so disposed that its surfacewhich tends to become conisjointed by means of a pin 3 to a link i, theop- 35 ent, invention from previous applications is the v and lever, I3.

the stop. If, however, the mechanism is to function on decrease oftemperature, the bi-metallic member must be reversed so that the surfacetending'to become concave on rise of temperature faces the stop. Thenormal set position of the toggle or knuckle joint may be determined bycontact, between one of its elements, or an extension thereof, and someother member. Nevertheless the stop 8 or its equivalentis required, butthedesign may be such that the bi-metallic' member I does not bear on ituntil a certaindethe temperature at which this action shall occur,

viation from the normal temperature has ccurred. If desired, the stopmay. be adjustable,

whereby the critical temperature at which the mechanism operates may bevaried.

Figures 2 and 3 depict a construction suitable for the control of anelectric circuit, this constructicn being applicable, for example, tothe ordinary domestic electric iron for the purpose of disconnecting theheating coil when the temperature rises above a predetermined criticalvalue. I In this case the bi-metallic member I and the complementarylink 4 of the toggle joint overlap, thati s to say, the latter member,which, asseen in Figure 3, is of U shape, extends from the pivot 3 inthe direction of the bi-metallic member I. This construction has theadvantage of minimising the total length of the mechanism and alsoresults in the bi-metallic member being, in a-state of tension ratherthan compression. The complementary link 4 is attached by pivots 9 totwo arms of a bent-metal frame I0 mounted on any appropriate fixedmember II. Pivoted on a pin I 2 extending through the frame it is alever I3'by means of which the electric switch or othermember to beactuated is operated, and to this lever the end of the bi-metallic stripI remote from the pin 3 is pivoted at I4, being maintained in tensionowing to the action of springs I5 bearing on the frame I 0 In thisinstance the bi-metallic strip is heated by virtue of its contact with ametal block I6, subject to the temperature variationwhich, it is desiredshall be effective in determining. action of the mechanism. In theabove-mentioned application of the device to an electric iron, the blockI6 may constitute a portion of the body of the iron itself whichisheated by the electrical Winding. The presence of this block renders thestop 8 unnecessary, since the block provides the required restraint onthe bimetallic member. It will be observed-that in the set or stableposition of the device the pivots 9 lieslightly to one side of astraight line joining thepivots 3 and I4, but on temperature variationin theappropriate sense the bi-metallic member becomes curved and, asthe above-mentioned straight line passes the centre line of the pivots9, the toggle joint collapses under the action of the springs I5,assuming the position indicated in chain-dotted lines. Obviouslyvariation of the sensitivity. of the device may be effected byadjustment of the position of the pivots 9 relatively to the linejoining the pivots -3 and M. This might be provided for in various ways;for example, the arms of the frame I0, instead of being rigid with theframe, might be hinged to it and adjustable in position by such means asa screw,

-i so that the pivots 9 are movable toward or away from the line joiningthe pivots 3 and M.

In the modification illustrated in Figure 4, the linkmembercomplementary to the bi-metallic member I is replaced by a ball I!capable of rolling within a guiding frame I8 attached to a lever 1 3.Temperature-actuated I9 pivoted at 2|] and biassed by means of a spring2| under tension. The bi-metallic member i is fitted with a block 22having a face substantially I at right angles to the length of themember and in. the set or stable position adapted to bear on the ball I!as shown. On'change of temperature, however, such as to cause the end ofthe bimetallic member to movein the direction indicated by an arrow, theball I! rolls down an inclined surface 23 on the block 22, thuspermitting the'lever I9 to'be'rocked under the action of the spring 2|.For the purpose of adjustment of they would normally be arranged so thattheir actions on change of temperature tend to reinforce each other. Itis conceivable, however, that the case might arise wherein adifferential action is; desirable.

In the claimingclauses which follow, it is to be understood that theterm toggle joint includes knuckle jointsand all similar mechanismscomprising two members between which there exists a connection of arelatively rotary nature.

What I claim and desire to secure by Letters Patent of the United Statesis:

, l. Temperature-actuated mechanism, comprising a, toggle jointconsisting in combination of, a bi-metallic toggle member, a pivot iorsaid toggle member, a 'secondtoggle member, a support for saidsecondtoggle member, said second toggle member beingmovable relativelyto said support and said toggle members being in mo-vable cooperativerelationship with each other, and. a yieldable force-applying memberconstructed and arranged to effect the collapse of said togglejointjwhen said bi-metallic member attains a predetermined-temperature.

-2'.. Temperature-actuated mechan sm, comprisinga itoggle jointconsisting in combination of two togglemembers whereof at least one isof bi-metallic construction, a pivotm connection for said members, asupporting pivot for one of said members, a movable support for theother or said members, a pivot connecting said other member withsaid-support and a yieldable force-applyingn'member constructed andarranged to effect the collapse of said toggle joint when saidbimetallic member attains a predetermined temperature'.. 3 i vmechanism, comprising'in combination'two toggle joint members whereof atleast one is of bi-metaliic construction, a pivot connecting saidmembers, a movable I support for one of said members, a second pivotconnecting oneof said members with said support, a-third pivotsupportingthe other or said members, means for adjusting said connecting pivottoward or away from a straight line joining said second'and third pivotswhenthe mechanismis in its stable position, and a yieldabieforce-applying member constructed and arranged to'effect the collapse ofsaid toggle joint when said bi-metallic member attains a predeterminedtemperature. I

4. Temperature-actuated mechanism, comprising in combination two togglejoint members whereof at least one is of bi-metallic construction, apivot connecting said members, a pivoted lever, a pivot connecting saidlever with one of 'saidmembers, a supporting pivot for the other ingpivot for said member, a ball in cooperative relationship with saidmemberfa movable support for said ball and whereon said ball may roll,and a yieldable force-applying member operatively associated with saidmovable support and constructed and arranged to effect the collapse ofsaid toggle joint when said bi-metallic member attains a predeterminedtemperature.

6. Temperature-actuated mechanism, comprising a toggle joint consistingcombination of a member of bi-metallicconstruction, a supporting pivotfor said member, a ball, a movable support for said ball and whereonsaid ball may roll, a block on said lei-metallic member having a surfaceon which said ball bears when said mechanism is in the stable positionand a secondsurface inclined to said first-mentioned surface on whichsupport and constructed and arranged to effect the collapse of saidtoggle joint when said 101- metallic member attains a predeterminedtemperature. v v i l 7. YA mechanism as in claim 2, wherein the membersoffsaid toggle joint extend in an, ap-

proximately straightline the one with the other when the mechanism. isin its stable position. 8.'A mechanism as in claim2, wherein the membersof said toggle joint overlap each other when the mechanism is initsstable position.

9. A mechanism as in claim 2, including a stop abutting against anintermediate point of said bi-metallic member.

10. A mechanism as in claim 2, including a stop abutting against anintermediate point of said bi-metallic member, said stop beingadjustable toward and away from said bi-metallic member. 11'.Temperature-actuated mechanism as in claim 6, wherein said block isadjustable relativelt to saidbi-metallic member in a direction parallelto said first-mentioned surface.

12. Temperature-actuated mechanism, comprising a pivoted lever, a toggleelement connected with the lever for movement relative thereto, a secondtoggle element coupled with the first element, a pivot for said secondelement, one of saidelements being of bi-metallic construction, afulcrum body engaged by the bimetallic element to cause movement of thelatter element in a desired direction when the latter element attains apredetermined temperature, and force-applying means coupled with saidlever to urge the same in a desired direction on a predetermined degreeof movement of the lei-metallic element. i

13. Temperature-actuated mechanism, combelow the pivot for the lever, atoggle member pivoted to the frame, a pivotal connection between theother end of said strip and said memher, the pivot of the] toggle memberto the frame lying between the pivoted ends of the strip and oifset fromthe line of said ends when the mechanism is in stable position, andyieldable forceapplying means connected with. said lever to effectoscillation of the toggle member and lever when said strip attains apredetermined temperature.

.14. Temperature-actuated mechanism, comprising a frame, a lever pivotedthereto, a bimetallic strip pivoted at one end to the lever below thepivot for the lever, a. toggle member pivoted to the frame, a pivotalconnection bemechanism isqin stable position, a fixed body engaged bysaid strip to forma bearing therefor against which the strip pressesupon fiexure, and yieldable force applying means connected with saidlever to effect oscillation of the toggle member and lever when saidstrip attains a predetermined temperature.

DONALD RUDOLF LAMBERT.

